for a given gene different people may have a different version (allele) of that gene

aneuploidy

incorrect number of chromosome sets, 3 sets instead of 2 for a human (ex)

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chromosome

long piece of DNA, can be seen with a microscope when it is coiled up into a stick like shape. humans have 22 autosomal chromosomes, 2 copies of each, plus either two X chromosomes (F) or and X and a Y (M)

Complex trait

trait or disease that arises because of the influence of many genes and environmental factors

copy-number variation

when a piece of a chromosome is missing or duplicated, the person has only one or three copies of that piece instead of the usual 2

consegregation

2 or more genetic markers that are inherited together are said to consegregate

diploid

cell or organism with 2 sets of chromosomes (humans)

endophenotype

a trait of biological origin that predisposes an individual for a certain disorder, biomarker

entrez

web portal for dozens of websitres relevant for genetics

exome

part of the genome that codes for proteins- 1.5% of the genome in humans, the sum of all the eons in a cell or organism

expression

people with the same genotype may show different traits, they differ in expression

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exon

region within a gene that codes for protein

fraternal twins

twins who developed from two separate fertilized eggs and differ genetically just like any other siblings differ from one another

gamete

egg cell or perm cell, only one set of chromosomes (haploid)

gene

sequences of DNA that code for certain proteins

genome

the entire nucleotide sequence on all chromosomes in a cell or organism

genotype

the specific nucleotide combination that a person has at a given locus

haploid

cell or organism with only one set of chromosomes

heterogeneity

a trait that can be influenced by different genes in different families, yet look similar on the surface (autism, etc.)

heterzygous

having 2 different versions of a piece of DNA in a given locus

homozygous

having 2 copies of the same version of a piece of DNA in a given locus

identical twins

twins who developed from the same fertilized egg and have the same DNA sequence

intron

region within a gene that lies between the eons and does not code for protein

karyotype

complete and ordered set of chromosomes as seen through a microscope

linkage analysis

statistical procedure to test DNA markers for con segregation with a trait or disease

all of a system considered together. Genome= entire DNA sequence in a cell or organism

OMM

online mendelian inheritance of man

Penetrance

the extent to which a risk genotype produces the disease. fully penetrant=all carriers have the disease. 90% penetrant- 9 or 10 carriers have the disease

phenotype

observable characteristics, normal trait or disorder

repeat expansion

a set of nucleotides gets copied more and more times with each successive generation

polymorphism

different people may have different versions of a gene all or which are normal

point mutation

a change in a single nucleotide, may or may not affect the carrier

sequencing

determine the nucleotide sequence of a part or of the entire genome

SNP

single nucleotide polymorphism.individual single nucleotides that vary from person to person and whose location on a chromosome is known precisely. the human genome has several milliion of SNPs and we use them as markers when we map genes to a location

syndrome

2 or more divergent symptoms occurring in the same affected individual, e.g. velocardiofacial syndrome affects craniofacial and heart structures

translation

the second step in the cell's process of making protein. a piece of messenger RNA is used as a template to creat a string of amino acids that forms a protein

transcription

the 1st step in the cells process of making protein. a rice of DNA creates a strand of messenger RNA (recipe for making proteins)

transcription factor

a gene that regulates how other genes work

variant

a piece of DNA that differs from that in the general population

zygote

single cell formed when a sperm fell and an egg cell unite. 2 sets of chromosome (diploid)